I am having issues building an Arduino module that can help me read what a pressure transducer outputs. I have an RS232 to TTL converter that is going to convert the data between the Arduino and the transducer, it looks like this:

The transducer has a D-sub15 connection, I made a cable for it so it has an D-sub9 end, the diagram looks like this (the cable looks terrible! But it works):

I have tested that the cable works by using an RS232 to USB cable, and using a serial terminal and sending the command to the transducer, and effectively receiving the ambient pressure (the command is: @253PR3?;FF).
However having the transducer connected to my computer is not efficient, so I want an Arduino to keep sending the string @253PR3?;FF while having the result in an LCD. As of now, I am just trying to have the Arduino send @253PR3?;FF through the TX pin and receiving data through the RX pin, then printing it in the serial monitor, obviously the TX, RX, VCC (5 or 3.3 V) and GND pins of the Arduino are connected to the max3232 converter.
The whole thing looks like this:

The code:
Code: Select all
String sensorValue;
void setup() {
Serial.begin(9600);
}
void Pressure() {
Serial.print ("@253PR3?;FF");
sensorValue = Serial.readString();
//sensorValue = sensorValue.remove(0, 7); //Go from @253ACK7.10E+2;FF to 7.10E+2;FF
//sensorValue = sensorValue.remove(7); //To get 7.39E+2
Serial.println (sensorValue);
}
void loop() {
//
Pressure(); //loop de sensorValue
}
Please help with anything you could see that could be the source of the problem,
Thanks